U.S. patent number 8,109,716 [Application Number 11/840,645] was granted by the patent office on 2012-02-07 for gas turbine engine systems involving hydrostatic face seals with anti-fouling provisioning.
This patent grant is currently assigned to United Technologies Corp.. Invention is credited to Jorn A. Glahn, Peter M. Munsell.
United States Patent |
8,109,716 |
Glahn , et al. |
February 7, 2012 |
Gas turbine engine systems involving hydrostatic face seals with
anti-fouling provisioning
Abstract
Gas turbine engine systems involving hydrostatic face seals with
anti-fouling provisioning are provided. In this regard, a
representative turbine assembly for a gas turbine engine comprises:
a turbine having a hydrostatic seal; the hydrostatic seal having a
seal face, a seal runner, a carrier, and a biasing member; the seal
face and the seal runner defining a high-pressure side and a
lower-pressure side of the seal; the carrier being operative to
position the seal face relative to the seal runner; and the biasing
member being located on the lower-pressure side of the seal and
being operative to bias the carrier such that interaction of the
biasing member and gas pressure across the seal causes the carrier
to position the seal face relative to the seal runner.
Inventors: |
Glahn; Jorn A. (Manchester,
CT), Munsell; Peter M. (Granby, CT) |
Assignee: |
United Technologies Corp.
(Hartford, CT)
|
Family
ID: |
39832370 |
Appl.
No.: |
11/840,645 |
Filed: |
August 17, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20090047124 A1 |
Feb 19, 2009 |
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Current U.S.
Class: |
415/168.2;
415/171.1; 415/174.2 |
Current CPC
Class: |
F01D
11/04 (20130101); F16J 15/342 (20130101); F01D
11/025 (20130101); F05D 2300/224 (20130101) |
Current International
Class: |
F01D
11/02 (20060101); F16J 15/34 (20060101) |
Field of
Search: |
;415/168.2,168.4,171.1,173.7,174.2,174.3,174.4,174.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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524515 |
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May 1931 |
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DE |
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102007027364 |
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Dec 2007 |
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DE |
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0523899 |
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Jan 1993 |
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EP |
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1348898 |
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Oct 2003 |
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EP |
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1380778 |
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Jan 2004 |
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EP |
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1780450 |
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May 2007 |
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EP |
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1798455 |
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Jun 2007 |
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EP |
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1852573 |
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Nov 2007 |
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EP |
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1366961 |
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Jul 1964 |
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FR |
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920782 |
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Mar 1963 |
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GB |
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1174207 |
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Dec 1969 |
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GB |
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Other References
The extended European Search Report of counterpart foreign
application No. EP 08252724 filed Aug. 14, 2008. cited by other
.
The extended European Search Report of counterpart foreign
application No. EP 08252690 filed Aug. 14, 2008. cited by
other.
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Primary Examiner: Wiehe; Nathaniel
Attorney, Agent or Firm: Kinney & Lange, P.A.
Claims
The invention claimed is:
1. A hydrostatic seal for a gas turbine engine comprising: a face
seal having a seal face; a seal runner, wherein the seal face and
the seal runner define a high-pressure side and a lower-pressure
side of the hydrostatic seal; a carrier, the face seal being
mounted to the carrier such that the carrier positions the seal
face with respect to the seal runner, wherein the face seal has an
air bearing supply channel extending from the high-pressure side to
a side on which the seal face is located, and wherein the carrier
has an orifice aligned with the air bearing supply channel; and a
shield attached to the carrier adjacent the orifice, the carrier
operative to form a physical barrier that discourages debris
travelling on a radially inward trajectory from entering the air
bearing supply channel and thereby reduces a potential for debris
to foul the hydrostatic seal formed by the seal face and the seal
runner.
2. The seal of claim 1, wherein: the seal further comprises a
biasing member operative to bias the seal face toward the seal
runner; and the biasing member being located on the lower-pressure
side of the seal.
3. The seal of claim 2, wherein the biasing member comprises a
spring.
4. The seal of claim 1, wherein: the seal comprises a stator
assembly; and the seal face is mounted to the stator assembly.
5. The seal of claim 1, wherein: the seal comprises a rotor
assembly; and the seal runner is mounted to the rotor assembly.
6. The seal of claim 1, wherein the air bearing supply channel
exhibits a straight configuration.
7. The seal of claim 6, wherein the air bearing supply channel
exhibits a non-uniform diameter along a length thereof.
8. A turbine assembly for a gas turbine engine comprising: a
turbine having a hydrostatic seal; the hydrostatic seal having a
seal face, a seal runner, a carrier, and a biasing member; the seal
face and the seal runner defining a high-pressure side and a
lower-pressure side of the seal, wherein the seal face is a surface
of a face seal, the face seal having an air bearing supply channel
extending from the high-pressure side to a side on which the seal
face is located; the carrier being operative to position the seal
face relative to the seal runner; a shield extending outwardly from
the carrier on the high-pressure side of the seal, the shield being
operative to discourage debris from entering the air bearing supply
channel; and the biasing member being located on the lower-pressure
side of the hydrostatic seal and being operative to bias the
carrier such that interaction of the biasing member and gas
pressure across the hydrostatic seal causes the carrier to position
the seal face relative to the seal runner.
9. The assembly of claim 8, wherein the air bearing supply channel
exhibits a straight configuration.
10. The assembly of claim 8, wherein the turbine is a low-pressure
turbine.
11. The assembly of claim 8, wherein the hydrostatic seal is
provided by a stator assembly and a rotor assembly, at least one of
which is removably mountable within the turbine.
12. The assembly of claim 8, wherein the hydrostatic seal is a
lift-off seal, with the seal face being biased to a contact
position in which the seal face contacts the seal runner.
13. The assembly of claim 8, wherein the air bearing supply channel
exhibits a non-uniform diameter along a length thereof.
14. The assembly of claim 8, wherein the carrier has an orifice
aligned with the air bearing supply channel.
15. A gas turbine engine comprising: a compressor; a shaft
interconnected with the compressor; and a turbine operative to
drive the shaft, the turbine having a hydrostatic seal; the
hydrostatic seal having a seal face, a seal runner, a carrier and a
biasing member; the seal face and the seal runner defining a
high-pressure side and a lower-pressure side of the seal, wherein
the seal face is a surface of a face seal, the face seal having an
air bearing supply channel extending from the high-pressure side to
a side on which the seal face is located; the carrier being
operative to position the seal face relative to the seal runner; a
shield extending outwardly from the carrier on the high-pressure
side of the seal, the shield being operative to discourage debris
from entering the air bearing supply channel; and the biasing
member being located on the lower-pressure side of the hydrostatic
seal and being operative to bias the carrier such that interaction
of the biasing member and gas pressure across the hydrostatic seal
causes the carrier to position the seal face relative to the seal
runner.
16. The engine of claim 15, wherein at least a portion of the seal
face configured to contact the seal runner is formed of a material
comprising carbon.
17. The engine of claim 15, wherein the engine is a turbofan.
18. The engine of claim 15, wherein the turbine is a low-pressure
turbine.
19. The engine of claim 15, wherein the air bearing supply channel
exhibits a straight configuration.
20. The engine of claim 15, wherein the air bearing supply channel
exhibits a non-uniform diameter along a length thereof.
Description
BACKGROUND
1. Technical Field
The disclosure generally relates to gas turbine engines.
2. Description of the Related Art
A gas turbine engine typically maintains pressure differentials
between various components during operation. These pressure
differentials are commonly maintained by various configurations of
seals. In this regard, labyrinth seals oftentimes are used in gas
turbine engines. As is known, labyrinth seals tend to deteriorate
over time. By way of example, a labyrinth seal can deteriorate due
to rub interactions from thermal and mechanical growths, assembly
tolerances, engine loads and maneuver deflections. Unfortunately,
such deterioration can cause increased flow consumption resulting
in increased parasitic losses and thermodynamic cycle loss.
SUMMARY
Gas turbine engine systems involving hydrostatic face seals with
anti-fouling provisioning are provided. In this regard, an
exemplary embodiment of a hydrostatic seal for a gas turbine engine
comprises: a face seal having a seal face; a seal runner; and means
for reducing a potential for debris to foul the hydrostatic seal
formed by the seal face and the seal runner.
An exemplary embodiment of a turbine assembly for a gas turbine
engine comprises: a turbine having a hydrostatic seal; the
hydrostatic seal having a seal face, a seal runner, a carrier, and
a biasing member; the seal face and the seal runner defining a
high-pressure side and a lower-pressure side of the seal; the
carrier being operative to position the seal face relative to the
seal runner; and the biasing member being located on the
lower-pressure side of the seal and being operative to bias the
carrier such that interaction of the biasing member and gas
pressure across the seal causes the carrier to position the seal
face relative to the seal runner.
An exemplary embodiment of a gas turbine engine comprises: a
compressor; a shaft interconnected with the compressor; and a
turbine operative to drive the shaft, the turbine having a
hydrostatic seal; the hydrostatic seal having a seal face, a seal
runner and a biasing member; the seal face and the seal runner
defining a high-pressure side and a lower-pressure side of the
seal; the biasing member being located on the lower-pressure side
of the seal and being operative to bias positioning of the seal
face relative to the seal runner.
Other systems, methods, features and/or advantages of this
disclosure will be or may become apparent to one with skill in the
art upon examination of the following drawings and detailed
description. It is intended that all such additional systems,
methods, features and/or advantages be included within this
description and be within the scope of the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
Many aspects of the disclosure can be better understood with
reference to the following drawings. The components in the drawings
are not necessarily to scale. Moreover, in the drawings, like
reference numerals designate corresponding parts throughout the
several views.
FIG. 1 is a schematic diagram depicting an exemplary embodiment of
a hydrostatic face seal with anti-fouling provisioning.
FIG. 2 is a schematic diagram depicting an exemplary embodiment of
a gas turbine engine.
FIG. 3 is a schematic diagram depicting a portion of the
low-pressure turbine of FIG. 2, showing detail of the embodiment of
the hydrostatic face seal with anti-fouling provisioning of FIG. 1
installed therein.
DETAILED DESCRIPTION
Gas turbine engine systems involving hydrostatic face seals with
anti-fouling provisioning are provided, several exemplary
embodiments of which will be described in detail. In this regard,
hydrostatic face seals can be used at various locations of a gas
turbine engine, such as in association with a low-pressure turbine.
Notably, a hydrostatic seal is a seal that uses balanced opening
and closing forces to maintain a desired separation between a seal
face and a corresponding seal runner. Use of a hydrostatic face
seal requires maintaining a metered airflow through orifices of the
seal in order to produce desired seal characteristics. Such a
metered airflow can be altered (e.g., interrupted) by the
introduction of debris, which may be present in the gas turbine
engine for a variety of reasons.
In order to reduce the possibility of a seal being fouled by
debris, some embodiments incorporate the use of one or more
anti-fouling provisions. By way of example, such provisions can
include locating one or more potential debris-producing components
of the seal to the lower-pressure side of the seal. Additionally or
alternatively, an air bearing supply channel of the seal that
limits the potential for debris to become stuck in the channel can
be used. For instance, in some embodiments, the channel does not
incorporate bends. Additionally or alternatively, an air bearing
supply channel can be shielded to prevent debris from entering the
channel.
An exemplary embodiment of a hydrostatic face seal with
anti-fouling provisioning is depicted schematically in FIG. 1. As
shown in FIG. 1, hydrostatic face seal 10 is provided by a
stationary stator assembly 12 and a rotating rotor assembly 14. The
stator assembly includes an arm 16 that extends from a mounting
bracket 18, which facilitates attachment, removal and/or position
adjustment of the stator assembly in the engine. Notably, other
embodiments may not incorporate such a mounting bracket.
Stator assembly 12 also incorporates a carrier 20 that carries a
face seal 22. Face seal 22 is annular in shape and includes a seal
face 24, which is one of the seal-forming surfaces of the
hydrostatic seal. A vent 25 also is provided through face seal
22.
Carrier 20 is axially translatable so that seal face 24 can move,
with the carrier, away from or toward (e.g., into contact with) a
seal runner 26 (which is the other of the seal-forming components
of the hydrostatic seal) of rotor assembly 14. In this embodiment,
an anti-rotation lock 28 is provided to prevent circumferential
movement and assist in aligning the seal carrier to facilitate
axial translation of the carrier.
A biasing member 30, which is provided as a spring in this
embodiment, biases the seal face against the seal runner until
overcome by gas pressure. Multiple springs may be disposed about
the circumference of the seal. In this regard, the biasing force of
the biasing member can be selected to maintain a desired pressure
differential between a high-pressure cavity (P.sub.HIGH) and a
lower-pressure cavity (P.sub.LOW) of the seal. Notably, a piston
ring 32 is captured between opposing surfaces 34, 36 of the stator
assembly and carrier, respectively, to control gas leakage between
the arm of the stator assembly and the carrier.
With respect to the rotor assembly 14, rotor assembly 14 supports
the seal runner 26, which is annular in shape. Specifically, the
rotor assembly 14 includes an arm 40 that extends from a mounting
bracket 42, which facilitates attachment, removal and/or position
adjustment of the rotor assembly 14. Notably, other embodiments may
not incorporate such a mounting bracket.
With respect to anti-fouling provisions, the embodiment of FIG. 1
incorporates several such means. For instance, seal 10 locates the
biasing member 30 in the lower-pressure cavity side (P.sub.LOW) of
the seal. Notably, the biasing member has the potential to produce
debris. By locating the biasing member on the lower-pressure cavity
side of the seal, any debris produced by the biasing member will
have a tendency to move away from the seal face and the seal runner
and, therefore, should not foul the seal. This is in contrast to a
seal that locates the biasing member on the high-pressure side. In
such an embodiment, debris from the biasing member can be drawn
(due to the pressure differential and corresponding gas flow across
the seal) between the seal face and seal runner, thus fouling the
seal.
As another example, seal 10 incorporates an air bearing supply
channel 46 that limits the potential for debris to become stuck in
the channel. Specifically, air bearing supply channel 46 is formed
through face seal 22 from a side 48 (which includes seal face 24)
to an opposing side 50 (which is attached to carrier 20). Notably,
carrier 20 includes an orifice 52 that is aligned with the air
bearing supply channel. So configured, air can be provided from the
high-pressure side of the seal, through orifice 52, then through
air bearing supply channel 46 to seal location 54, which is located
between side 48 and seal runner 26.
In order to reduce the potential for debris to become stuck in the
air bearing supply channel, channel 46 of the embodiment of FIG. 1
does not incorporate bends. That is, the channel is a substantially
straight through-hole. While a constant diameter straight
through-hole is less susceptible to debris accumulation when
compared with internal passages that have sharp bends, it is
preferable to tailor the diameter along the tube towards a desired
pressure distribution. Thus, in the embodiment of FIG. 1, channel
46 includes a cylindrical portion 45 that is interconnected with a
cylindrical portion 47 (of smaller diameter) via a conical portion
49 such that the channel exhibits a non-uniform diameter along its
length. It should be noted that the cylindrical portion 47 could be
connected to orifice 52 without incorporation of a cylindrical
portion 45. In this case, the non-uniform diameter of the channel
inside face seal 22 consists of a lead-in conical portion 49 and
the cylindrical section 47. Connecting cylindrical portions 45 and
47 with a conical portion 49 accelerates the flow and reduces
residence times of any debris particles. Therefore, the potential
for debris accumulation is reduced.
Alternatives to straight through-hole configurations that may
reduce a tendency for debris to get stuck in the internal face seal
channels could involve internal cavities that serve reservoirs.
These could be formed by relatively large diameter holes drilled
radially inward and deeper than that needed to feed an axial air
bearing supply hole, which is typically similar to cylindrical
portion 47.
Seal 10 also incorporates a shield for reducing the potential of
debris to enter the air bearing supply channel. Specifically, a
shield 60 is provided that extends outwardly from carrier 20 in a
vicinity of orifice 52. The shield forms a physical barrier that
discourages debris travelling on a radially inward trajectory from
entering the orifice. Additionally, for debris to enter orifice 52
of the embodiment of FIG. 1, the debris is required to pass through
a narrow opening 62 defined by the shield and a surface 64 of the
carrier. Notably, since the orifice is located radially outboard of
surface 64, the tortuous path formed by the shield and the orifice
location may prevent debris from entering the air bearing supply
channel.
FIG. 2 is a schematic diagram depicting an exemplary embodiment of
a gas turbine engine, in which an embodiment of a hydrostatic face
seal with anti-fouling provisioning can be used. As shown in FIG.
2, engine 100 is configured as a turbofan that incorporates a fan
102, a compressor section 104, a combustion section 106 and a
turbine section 108. Although the embodiment of FIG. 2 is
configured as a turbofan, there is no intention to limit the
concepts described herein to use with turbofans, as various other
configurations of gas turbine engines can be used.
Engine 100 is a dual spool engine that includes a high-pressure
turbine 110 interconnected with a high-pressure compressor 112 via
a shaft 114, and a low-pressure turbine 120 interconnected with a
low-pressure compressor 122 via a shaft 124. It should also be
noted that although various embodiments are described as
incorporating hydrostatic face seals with anti-fouling provisioning
in low-pressure turbines, such seals are not limited to use with
low-pressure turbines.
As shown in FIG. 3, low-pressure turbine 120 defines a primary gas
flow path 130 along which multiple rotating blades (e.g., blade
132) and stationary vanes (e.g., vane 134) are located. In this
embodiment, the blades are mounted to turbine disks, the respective
webs and bores of which extend into a high-pressure cavity 140. For
instance, disk 142 includes a web 144 and a bore 146, each of which
extends into cavity 140.
A relatively lower-pressure cavity 148 is oriented between
high-pressure cavity 140 and turbine hub 150, with a seal 10
(described in detail before with respect to FIG. 1) being provided
to maintain a pressure differential between the high-pressure
cavity and the lower-pressure cavity. Recall that seal assembly 10
incorporates a stator assembly 12 and a rotor assembly 14. Notably,
the stator assembly is mounted to a non-rotating structure of the
turbine, whereas the rotor assembly is mounted to a rotating
structure. In the implementation of FIG. 3, the rotor assembly is
mounted to turbine hub 150.
It should be noted that seal 10 is provided as a removable
assembly, the location of which can be adjusted. As such, thrust
balance trimming of engine 100 can be at least partially
accommodated by altering the position of the seal assembly.
In operation, the seal face intermittently contacts the seal
runner. By way of example, contact between the seal face and the
seal runner can occur during sub-idle conditions and/or during
transient conditions. That is, contact between the seal face and
the seal runner is maintained until gas pressure in the
high-pressure cavity is adequate to overcome the biasing force,
thereby separating the seal face from the seal runner. During
normal operating conditions, however, the seal face and the seal
runner should not contact each other.
Since the embodiments described herein are configured as lift-off
seals (i.e., at least intermittent contact is expected), materials
forming the surfaces that will contact each other are selected, at
least in part, for their durability. In this regard, a material
comprising carbon can be used as a seal face material. It should be
noted, however, that carbon can fracture or otherwise be damaged
due to unwanted contact (e.g., excessively forceful contact)
between the seal face and the seal runner as may be caused by
pressure fluctuations and/or vibrations, for example. It should
also be noted that carbon may be susceptible to deterioration at
higher temperatures. Therefore, carbon should be used in locations
where predicted temperatures are not excessive. By way of example,
use of such a material may not be appropriate, in some embodiments,
in a high-pressure turbine.
It should be emphasized that the above-described embodiments are
merely possible examples of implementations set forth for a clear
understanding of the principles of this disclosure. Many variations
and modifications may be made to the above-described embodiments
without departing substantially from the spirit and principles of
the disclosure. By way of example, although the embodiments
described herein are configured as lift-off seals, other types of
seals can be used. All such modifications and variations are
intended to be included herein within the scope of this disclosure
and protected by the accompanying claims.
* * * * *